Semiconductor devices such as complementary metal oxide semiconductor (CMOS) transistors continue to be scaled to smaller sizes to meet advanced performance targets. Fabrication of devices with such small dimensions involves precise control. For example, a method for forming a deep trench generally includes multiple steps of etching, deposition, and patterning. An increasing number of trench structures are fabricated in a limited space of a semiconductor substrate. The trenches should also be in good alignment with other device portions without any defects. Examples of applications of deep trench structures include deep trench isolations (DTI) and deep trench capacitors (DTC).
Meanwhile, as the semiconductor devices having very large scale integrated (VLSI) circuits shrink to a smaller size, and are operated at higher frequency, higher amounts of heat are generated. For example, CMOS transistors may generate a large amount of heat, which can cause undesired leakage currents. Therefore, heat removal techniques become important.